fix(data): backfill invalid dossier for tiers without tiers info

app/tasks/maintenance/backfill_invalid_dossiers_for_tiers_task.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+module Maintenance
+  class BackfillInvalidDossiersForTiersTask < MaintenanceTasks::Task
+    def collection
+      Dossier.where(for_tiers: true).where(mandataire_first_name: nil)
+    end
+
+    def process(element)
+      element.update_column(for_tiers: false)
+    end
+  end
+end